Study of an Argentine mistletoe, the hemiparasite Ligaria cuneifolia (R. et P.) Tiegh. (Loranthaceae)

Ligaria cuneifolia (R. et P.) Tiegh. is an hemiparasite species used in Argentine folk medicine as a substitute for the European mistletoe (Viscum album L.) based on its putative activity of decreasing high blood pressure. This paper analyzes flavonoid composition, protein constituents and the possible immunomodulatory and antitumoral effects of this species. Micromolecular study disclosed quercetin-free, quercetin-glycosylated and proanthocyanidins corresponding to cyanidin monomers, which implies a particular metabolic pathway. Proteins present in L. cuneifolia extracts analyzed by SDS-PAGE presented multiple bands with molecular weights ranging from 14 to 90 kD. These features contribute to the characterization of the native mistletoe. As V. album is being used in cancer treatment due to its immunomodulatory and antitumoral activity, the action of aqueous L. cuneifolia extracts on murine lymphocytes was investigated. Culture of murine spleen cells alone or stimulated with Concanavalin A or lipopolysaccharide in presence of L. cuneifolia extracts indicated a certain stimulation of splenocytes alone and an inhibition of splenocytes stimulated with Concanvalin A or lipopolysaccharide. An inhibitory effect was also observed on the proliferation of murine leukemia cells. In addition, aqueous extracts increased nitric oxide production by murine macrophages. These results suggest that L. cuneifolia extracts exert an immunomodulatory effect on the mouse immune system.